Researchers at Rutgers Health, publishing in Nature Mental Health, analyzed genetic data from more than 2.2 million individuals across prior genome-wide association studies.
Their goal was to map the genetic roots of alcohol, tobacco, cannabis, and opioid use disorders. What they found could change the way clinicians think about who is most at risk and why.
How Genes Shape Addiction Risk
Most of the genetic risk for developing a substance addiction comes from genes that broadly affect how the brain processes rewards, regulates impulses and weighs consequences, not from genes specific to any single substance.
The Rutgers team, led by faculty instructor Holly Poore, identified two distinct genetic pathways at work. The first is a broad “behavioral disinhibition” pathway, sometimes called an externalizing pathway, tied to brain systems governing self-control, reward-seeking, and risk-taking.
This pathway cuts across many forms of addiction and is associated with conditions like ADHD, conduct problems and impulsivity. The second involves substance-specific genetic pathways, for example, genes that affect alcohol metabolism or nicotine receptor function.
Senior author Danielle Dick, director of the Rutgers Addiction Research Center, described the finding this way.
The same genes appear across many behavioral outcomes, with substance-specific genes layered on top. The study, she said, teases those two pathways apart at the genomic level for the first time.
What This Means for Personalized Addiction Treatment
Understanding the genetic architecture of addiction opens new doors for how drug rehab and mental health treatment programs are designed and delivered.
The researchers developed polygenic scores, summary measures that combine thousands of genetic variants into a single index of genetic liability.
Broad externalizing scores were especially powerful in predicting risk across multiple substance use disorders, while substance-specific scores provided more precise information about vulnerability to particular drugs like alcohol or nicotine.
This two-tier picture matters for treatment seekers. Someone entering rehab with a strong family history of addiction and co-occurring ADHD or conduct problems may carry elevated genetic liability across the board.
This means their treatment plan may benefit from addressing impulse regulation alongside substance use directly.
Dick noted that a broader genetic metric can indicate who is generally more vulnerable to addiction and externalizing problems, while more substance-specific scores can help identify risk for particular substances.
Critically, she emphasized that genes do not determine destiny, but they can help identify who might benefit most from earlier intervention and targeted prevention.
Co-Occurring Conditions and the Case for Integrated Care
One of the study’s most clinically relevant findings involves the overlap between addiction genetics and other psychiatric conditions.
Many of the genes linked to the broad externalizing pathway also overlap with genes implicated in other psychiatric and substance-related disorders, underscoring shared biology across conditions.
This reinforces the growing clinical case for integrated addiction treatment programs that address mental health alongside substance use, often referred to as dual diagnosis or co-occurring disorder treatment.
The researchers also conducted network and drug-target analyses identifying potential biological systems and existing medications that could be repurposed for addiction treatment, a finding that points toward future pharmacological options beyond those currently available.
Limitations and the Need for Diverse Research
The study’s analyses were limited to individuals of European ancestry, reflecting the current availability of large-scale genetic datasets.
The researchers emphasized the urgent need for more diverse genomic research to ensure findings are relevant and equitable across populations.
This limitation is important for treatment providers to understand when applying these findings to diverse patient populations. Rehab centers serving communities with varied racial and ethnic backgrounds should watch for updated research as the field expands.
If you or someone you love is researching addiction treatment options, this research reinforces something clinicians have long observed, addiction rarely occurs in isolation.
A comprehensive intake assessment at a quality rehab center should account for behavioral history, co-occurring mental health conditions, and family history, all of which may reflect the genetic pathways this research identifies.
Facilities offering dual diagnosis treatment, trauma-informed care, and individualized treatment planning are best positioned to address the full biological picture this study reveals.
Finding the Right Rehab
This research underscores why one-size-fits-all addiction treatment often falls short. When evaluating rehab centers, consider asking about their use of evidence-based therapies and whether treatment plans are individualized based on a thorough assessment.
Rehab.com’s directory includes thousands of certified rehab centers nationwide. Call
800-985-8516
( 
Sponsored Helpline )
to speak with a treatment advisor who can help match you to the right level of care.
